SSL_ERROR_NO_CYPHER_OVERLAP
Your server apparently doesn't offer any cipher suites necessary to establish a
secure https connection that are supported in Firefox. You can check what kind
of cipher suites Firefox can make use of by visiting;
https://www.ssllabs.com/ssltest/viewMyClient.html

There is security software like Avast, Kaspersky,
BitDefender and ESET that intercept secure
connections and send their own certificate.
https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can
https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites
https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message
https://support.mozilla.org/en-US/kb/connection-untrusted-error-message
http://kb.mozillazine.org/Error_loading_websites
'''SSL_ERROR_NO_CYPHER_OVERLAP'''
Your server apparently doesn't offer any cipher suites necessary to establish a
secure https connection that are supported in Firefox. You can check what kind
of cipher suites Firefox can make use of by visiting;
https://www.ssllabs.com/ssltest/viewMyClient.html

Question owner

I have no anti virus software installed.

Results of the SSL labs test

Protocol Support
Your user agent has good protocol support.
Your user agent supports TLS 1.2, which is recommended protocol version at the moment.
Experimental: Your user agent supports TLS 1.3.
Logjam Vulnerability
Your user agent is not vulnerable.
For more information about the Logjam attack, please go to weakdh.org.
To test manually, click here. Your user agent is not vulnerable if it fails to connect to the site.
FREAK Vulnerability
Your user agent is not vulnerable.
For more information about the FREAK attack, please go to www.freakattack.com.
To test manually, click here. Your user agent is not vulnerable if it fails to connect to the site.
POODLE Vulnerability
Your user agent is not vulnerable.
For more information about the POODLE attack, please read this blog post.
Protocol Features
Protocols
TLS 1.3 Yes
TLS 1.2 Yes
TLS 1.1 Yes
TLS 1.0 Yes
SSL 3 No
SSL 2 No